This invention relates to a method of designating an extreme-value channel of which level of an envelope signal is the greatest or smallest, in an electronic musical instrument having a plurality of tone generating channels. The invention is suitably used for example in the truncating process of the musical instrument.
In assigning tone generation of a newly depressed key to any of plural tone generating channels when all the channels have already been assigned or occupied, it has been conventional to detect, as a truncating channel, a channel where attenuation of the tone signal has progressed to the farthest degree of all the channels and then to assign the tone generation of the newly depressed key to this truncating channel. Prior art related to such truncating process is shown such as in U.S. Pat. No. 4,114,495 (corresponding to Japanese Patent Application Laid-open No. Sho-52-25613) and U.S. Pat. No. 4,703,680 (corresponding to Japanese Patent Publication No. Hei-1-28397 and Japanese Patent Application Laid-open No. Sho-61-270799).
However, none of the prior art truncating devices have been satisfactory in that the number of the channels to which the truncating process is applied (the truncating-process object channels) is fixed by hardware and can not be expanded as required.